Answer:
v = 0.6 v₁
Explanation:
This is an exercise in collisions, let's start by defining a system formed by the two bodies, so that the forces during the collisions have been internal and the momentum is preserved.
Instant starts. Before the crash
p₀ = M v₁ + m 0
Final moment. After the crash
[tex]p_{f}[/tex] = (M + m) v
how momentum is conserved
p₀ = p_{f}
M v₁ = (M + m) v
v = [tex]\frac{M}{M+m} v_{1}[/tex]
let's calculate
v = [tex]\frac{15}{15+10} v_{1}[/tex]
v = 0.6 v₁